Is there a name for this browser technique?

Question

Is there a name for this technique, which is to open a page open in a browser, to find specific content and change it?

Some examples:

• Skype finds the phone numbers on the page and attaches the call menu
• a script finds the percentages on the page and replaces them with a small pie
• the advertising engine finds keywords on the page and converts them into hyperlinks
• add an icon next to all hyperlinks on the page that point to another domain
• and etc.

I understand that this is a kind of progressive perfection. But I am particularly interested in the first step - the process of detecting content. I would be interested in articles that offer best practices, or explain the flaws of this technique.

Edit: I added an example to show that this method is not only for text nodes, but can be applied to any type of html content.

Answer 1

For example, execute this code for this web page (from the console) and all numbers on the page will be replaced with "X":

function walkTheDOM( node, func ) {
    func( node );
    node = node.firstChild;
    while ( node ) {
        walkTheDOM( node, func );
        node = node.nextSibling;
    }
}

walkTheDOM( document.body, function ( node ) {
    if ( node.nodeType === 3 ) {
        node.data = node.data.replace( /\d/g, 'X' );
    }
});

Answer 2

This functionality is called add-ons , and the technique they use is to move the DOM

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Answer 3

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Answer 4

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